The present invention relates to an angioplasty device which can take the form of a hollow metallic guide wire with a balloon mounted on the distal end thereof.
Balloon angioplasty is an effective method for treating vascular disease, especially atherosclerosis. The build up of plaque in the lumen of a blood vessel, i.e. a stenosis, narrows the lumen and may possibly totally occlude the lumen if left untreated. Such a situation in a coronary artery is known as a myocardial infarction, i.e. a heart attack.
Prior to the advent of balloon angioplasty, the treatment for a stenotic lesion in a blood vessel was bypass surgery. This required an artificial graft or one of the patient's other blood vessels to be used to bypass the diseased vessel. In order to properly position the replacement blood vessel, major surgery was required to give the physician access to the body site to be treated so the replacement blood vessel could be sewn in place.
In balloon angioplasty, a balloon located on the distal end of a catheter is used to expand the blood vessel to restore its patency in the area of the stenotic lesion. The existence and location of a stenotic lesion is first determined by using a diagnostic catheter to inject contrast fluid to the affected area which is viewed under fluoroscopy.
Where a coronary artery is to be treated, i.e., in a PTCA (percutaneous transluminal coronary angioplasty) procedure, the balloon dilatation catheter typically enters the body at an access site, typically at the femoral artery, remote from the blood vessel to be treated and is maneuvered in the vascular system to the treatment site. Before a balloon dilatation catheter can be maneuvered into place, a guide catheter, with a J wire disposed therein and extending beyond the distal end, is typically inserted into the femoral artery in the groin area and maneuvered through the vasculature, around the aortic arch, where the J wire is removed, to the appropriate coronary ostium for the coronary artery to be treated. The guide catheter provides backup support for advancement of the balloon dilatation catheter to the treatment site. The guide catheter also allows adequate amounts of contrast fluid to be injected therethrough with the balloon dilatation catheter therein so the physician can visualize the treatment site under fluoroscopy during the procedure.
Where a wire guided balloon dilatation catheter, i.e. an over the wire balloon dilatation catheter or a rapid exchange balloon dilatation catheter, is to be used, a metallic guide wire will be guided through the guide catheter to the treatment site first to provide a path over which the balloon dilatation catheter can travel. The guide wire is inserted in the guide catheter so it extends past the distal end of the guide catheter and across the stenotic lesion to be treated. This provides the balloon dilatation catheter with access to the stenotic lesion to be treated.
Where a fixed wire balloon dilatation catheter is used, no separate guide wire is needed. Instead the balloon dilatation catheter has a wire fixed to it that serves to guide the balloon dilatation catheter to the treatment site.
One problem that may occur is when the stenosis substantially occludes the lumen of the blood vessel. If the profile (outer diameter) of the balloon dilatation catheter is too large, it will be unable to cross the lesion to allow the balloon to inflate and restore patency to the blood vessel. A related problem occurs when the stenosis is located in a very narrow blood vessel. These lesions may be inaccessible to a standard balloon dilatation catheter, which has a typical outer diameter of about 0.032 to about 0.036 inches (about 0.081 cm to about 0.091 cm) along its distal portion. Although guide wires which have an outer diameter of 0.014 inches to 0.018 inches (0.036 cm to 0.046 cm) may be able to cross a very tight stenosis in an extremely narrow blood vessel, such guide wires can not dilate the stenosis.
Another problem may occur in a balloon angioplasty procedure where the physician may have to use more than one balloon dilatation catheter, i.e. exchange balloon dilatation catheters, if the balloon on the original balloon dilatation catheter is not of the proper size to safely and fully treat the stenotic lesion. This is not a major problem for wire guided balloon dilatation catheters because the guide wire can remain in place across the stenosis while the balloon dilatation catheters are exchanged. On the other hand, if a fixed wire balloon dilatation catheter is used, access to the stenotic lesion will be lost if that catheter is removed.
After the angioplasty procedure, a stent may be used to support the vessel wall. These stents are used to enlarge and support the lumen, provide a smooth luminal surface, reinforce vessel dissections, tack-up tissue flaps, reduce the risk of plaque rupture, decrease the incidence of complications and reduce the incidence of restenosis. Many different types of stents may be used, such as radially self-expanding stents or balloon-expandable stents. Typically, the stent is placed on the distal end of a wire guided delivery catheter so the stent can be maneuvered adjacent to the treatment site and deployed there. After deployment it may be necessary in certain circumstances to expand the stent further after it has been deployed. This requires the use of an additional balloon catheter that must be maneuvered to the stent so the balloon can expand the stent further. Because of all of the steps and the different devices necessary to perform this procedure, the risk of trauma to the patient is high.
It is therefore an object of the invention to provide an angioplasty device that can cross a very tight stenosis or cross an extremely narrow blood vessel and dilate a stenotic lesion.
It is a further object of this invention to provide an angioplasty device that acts as a guide wire that can predilate a stenosis.
It is still a further object of this invention to provide an angioplasty device that can be used with typical angioplasty balloon dilatation catheters where a balloon exchange is indicated.
It is yet another object of the invention to provide an angioplasty device that minimizes the number of different interventional devices needed to perform balloon angioplasty and further expand a stent at the site of the angioplasty procedure.